In several industries, and in particular the food industry, there is a need to separate liquid greases, fats and oils from waste water prior to passing the water to the sewage system. The waste water could be, for example, discharged from a washing device for cleaning dinnerware and cooking utensils. If the greases and fats solidify in the sewage system, a blockage can occur which is expensive to remediate.
It has been found that the liquid wastes from kitchens are often immiscible mixtures of water and oils. As is well known, a first immiscible liquid of one specific gravity will float on a second immiscible liquid having a greater specific gravity. It has also been experimentally determined that the general kitchen waste oils have a specific gravity of about 0.92-0.93, whereas the specific gravity of water is about 1.0. As such, the kitchen oils float on top of the waste water. It has further been determined that in typical immiscible liquid separators, the level of the oil floating on top of the waste water is higher by a calculated distance than the level of the separated waste water itself. The “calculated distance” can be determined for different liquids from prior art teachings. Accordingly, in many prior art immiscible separation units, the highest level of the release valve or oil outlet that releases the oils from the separator is the calculated distance higher than the weir over which the separated waste water flows in order to exit the immiscible liquid separation unit. If the separator is operating within its design limits, then when the proper vertical location of the oil outlet is adhered to, it is assured that the waste water in the separation chamber will not rise sufficiently to inadvertently exit the oil outlet of the separator.
U.S. Pat. No. 7,297,284 by Owen et al., discloses various embodiments of immiscible liquid separators. Described therein are parameters that are important when considering the construction of a separator to separate the oil content from the water content of a waste liquid. Two immiscible liquids of different specific gravities will separate under the force of gravity into two separate layers in a calculable or measurable time period, according to Stokes Law. Typical immiscible liquid separators are constructed with a separation chamber of sufficient size to allow the waste liquid to separate therein, with the oil floating on top of the water. As more waste liquid is added to the separator, the floating oil rises and overflows via an oil outlet into an oil reservoir. The previously separated water flows from the separation chamber under a separator plate into a water chamber where, when the level is sufficiently high, the separated water overflows over a fixed height weir and out of the separator. If the mixture of two immiscible liquids is introduced into the separation chamber at a known flow rate, then the chamber can be sized to ensure that separation is completed before the heavier liquid (water) flows under the separation plate to the separated water chamber.
In the prior art immiscible liquid separators, the weir is often a planar plate that extends laterally between sidewalls of the separator. Thus, when waste liquid influents enter the separator and are separated, the separated waste water flows over the weir and exits the separator and is drained away via the water drainage system. The separated waste water flows over the linear weir much like excess flood water flows over a spillway, dam or levy. This type of immiscible liquid separator works well when fastened to a level floor, or the like, so that the top of the weir is level. If the separator is not level, then the weir can be tilted and the incoming waste liquid influent does not lift the floating oil in the vicinity of the release ball valve sufficiently to allow the oils to be discharged out of the ball valve. In other words, if the liquid separator is tilted in such a way that the water weir is greater than the calculated distance above the oil exit level of the ball valve, then the waste liquids drained into the separator will either not lift the floating oil high enough to exit the ball valve, or will allow the water to rise higher than it should in the separation chamber and exit the oil exit of the separator. Either of these results degrades the operation of the separator unit.
Immiscible liquid separators can be mounted in restaurants, and the like, at desired orientations so as to be level and operate under optimal conditions. However, there are situations where this is not always possible. For example, restaurants and food preparation facilities on ships and other marine vessels are themselves not maintained level, as the ship's pitch and roll motion causes all equipment mounted thereto to move accordingly. As such, the ability to maximally separate the immiscible liquids with conventional separators is compromised. As a result of the constant motion of ships, the waste products are often not processed through immiscible liquid separators, but rather are simply flushed into a holding tank that is emptied when the ship arrives at a port. Under current international rules and regulations, ships cannot dump the holding tanks into the ocean when within about 35 miles of shore. Otherwise, it is a current practice for ships to dump the waste material overboard before reaching the 35-mile limit. Moreover, when ships equipped with holding tanks do empty the waste material at shore facilities, the costs can be significant, as shore facilities must be available to then accept and process the wastes and dispose of the same in an environmentally safe manner. At this point, the fat, oil and grease content of the waste material have degraded to a point where they are not suitable for recycling.
From the foregoing, it can be seen that a need exists for an immiscible liquid disposal system which separates the waste water and oils irrespective of the orientation thereof. Another need exists for an immiscible liquid separator adapted for marine use so that the separated water can be released in the ocean and the oils can be either burned as fuel by the ship engines, or temporarily stored and transferred to a shore facility for sale to a recycling company. A further need exists for an immiscible liquid separator constructed so that the oil outlet level is always the calculated distance above the water outlet level, and is independent of the orientation of the immiscible liquid separator unit.